var record = [];

exports.create = function(obj) {
    record.push(obj);
};

exports.find = function(callback) {
    callback.apply(null, [record]);
};

exports.findById = function(id, callback) {
    if (id >= record.length) {
        var err = new Error('Not Exists');
        callback.apply(null, [err]);
    } else {
        callback.apply(null, [null, record[id]]);
    }
};